(No, urban/city violence is on the rise..[0])
At best license plate cameras seem like they might deter bad driving if they make it easier to issue citations to bad drivers. I cannot imagine how they would meaningfully impact armed robberies or other violent crime. It's just more surveillance that in practice probably increases police dept income (via tickets). Maybe it slightly reduces the time police officers spend in courtrooms or writing up tickets, leaving them more time to respond to calls?
Don't let yourself get tricked into rubber stamping warrantless surveillance just because you want to be safer in some other area.